How did oil forms so deep Underground away from all organic vegetation?

Answer 1

The botany of a specific area changes quite a bit over the course of several million years. Large portions of what is currently the Sahara Desert was lush forest land. As time passes, sediment accumulates over the surface of the Earth (some places more than other of course). The biology of the area(any area) is going to change given enough time. So you have all of this decomposing organic material that is buried by hundreds, if not thousands of feet of sediment, where they turn into hydro-carbon chains of varying length(crud oil). Coal is formed much in the same way. This is just a basic explanation of the process, for more in depth information, there are many very informative sites with detailed writings on the subject. The best way to find them is through a simple search engine(Yahoo,Google,Ask.com....
Hope this helps, best wishes, Jack

Answer 2

it started out as decaying plant matter and dinosaur poop that was forced underground by sediment and earthquakes and geophysics and stuff. Once under pressured to heat, it formed into oil